In undergraduate chemistry curricula, for highly diluted strong acid or base solutions, to avoid excessive error in estimating its pH value, systematic treatment of two related chemical equilibria is normally required. Such approach nornmally sets the concentration of hydrogen ions as the unknown and yields a quadratic equation. Solving such quadratic equation yields two roots with opposite signs: the positive root giving the value of the hydrogen ion concentration and the negative root was assumed to hold no significant value. Our research indicated that the absolute value of this negative root is the hydrogen ion concentration from the autoprotolysis of water in such solution. This derivation example may be used in undergraduate curricula to improve the students' understanding on the systematic treatment of equilibria.

Unexpected application of the negative root in systematic treatment of solving the pH of a diluted strong acid or base solution

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.